Water fill arrangement for clear cube ice maker

ABSTRACT

A tilt-stem valve controlling the flow from a household water line to a water reservoir for a refrigerator ice maker. The reservoir has a float pivotally supported therein on a transverse pivot at a top end wall edge of the float intermediate the valve upper inlet and the subjacent reservoir outlet. The valve stem extends vertically downwardly from the valve plug beyond the float bottom wall whereby upon a fall in the water level pivots the float into engagement with the distal end of the stem to open the valve providing improved sensitivity to changes in the reservoir water level obviating the need for user adjustment of the water level in the ice maker tray throughout a domestic water pressure range of about 20 to 120 psi.

United States Patent [191 Bright 1 Nov. 25, 1975 WATER FILL ARRANGEMENT FOR CLEAR CUBE ICE MAKER [75] Inventor: James A. Bright, Dayton, Ohio [73] Assignee: General Motors Corporation,

Detroit, Mich.

[22] Filed: Nov. 27, 1974 [21] Appl. No.: 527,628

[56] References Cited UNITED STATES PATENTS Storer 62/188 X Henderson. 62/353 Archer 62/353 X Primary Examiner-William E. Wayner Assistant Examiner-William E. Tapolcai, Jr. Attorney, Agent, or Firm-Edward P. Barthel [57] ABSTRACT A tilt-stem valve controlling the flow from a household water line to a water reservoir for a refrigerator ice maker. The reservoir has a float pivotally supported therein on a transverse pivot at a top end wall edge of the float intermediate the valve upper inlet and the subjacent reservoir outlet. The valve stem extends vertically downwardly from the valve plug beyond the float bottom wall whereby upon a fall in the water level pivots the float into engagement with the distal end of the stem to open the valve providing improved sensitivity to changes in the reservoir water level obviating the need for user adjustment of the water level in the ice maker tray throughout a domestic water pressure range of about 20 to 120 psi.

4 Claims, 10 Drawing Figures US. Patent N0v.25, 1975 Sheet10f4 3,921,414

U.S., Patent Nov. 25, 1975 Sheet2of4 3,921,414

US. Patent Nov. 25, 1975 Sheet3of4 3,921,414

5 5 111107111! n lllllllll- US, Patent Nov. 25, 1975 P (WATER PRESSURE) PRESSURE P FORCE KZI/ Sheet 4 0f 4 WAT'ER LEVE (FLOAT FORCE) P= DENSITY OF WATER w (FLOAT WEIGHT) l (VALVE EoRcE) WATER FILL ARRANGEMENT FOR CLEAR CUBE ICE MAKER This invention relates to automatic ice makers for domestic refrigerators and in particular to a water refill arrangement and improved reservoir having a tilt-valve water inlet.

In one form of a clear automatic ice maker for a domestic refrigerator disclosed in the U.S. Pat. No. 3,775,992 issued Dec. 4, 1973 to James A. Bright and assigned to the assignee of the. instant invention, a water fill system is disclosed for supplying water to the ice cube tray or mold of an automatic ice maker from a water valve reservoir housing having a pivoting float positioned thereon and wherein the housing is attached to the back wall of the refrigerator. Water in the reservoir communicates with the tray through an outlet in the reservoir housing and conduit means connecting the outlet with the tray fill tube. Water contained in the tray seeks a common level with water in the reservoir whereby the desired fill level in the tray is achieved by predetermining the water level in the reservoir. The Bright patent discloses controlling the water level in the reservoir housing by a float pivotally attached therein while the top wall of the housing carries a water valve assembly including a valve pin slidably supported for vertical movement on a plurality of vertical ribs having a rubber valve portion thereon adapted for closing against the valve seat. At the lower end of the assembly a valve pin actuator pivots about an axis in response to the upward force of the float at one end as balanced against a water level adjustment mechanism at the other end such that the water level may be adjusted by a remote knob turning worm gears against a biasing spring. The water level is adjusted in a manner to shut off the water supply when a predetermined water level exists in both the reservoir and tray after a fresh charge of water is supplied to the tray during an ice harvesting cycle when the grid is out of the tray.

It is an object ofthe present invention to provide an improved water fill system for an automatic ice maker including a tilt-stem valve water inlet controlling flow to a reservoir having a pivotal float therein providing greater sensitivity to changes in the water level obviating the need for user adjustment of the water level in the ice maker tray throughouta domestic water pressure range of about to 120 psi.

It is a further object of the present invention to provide an improved water fill system for an automatic ice maker including a tilt-stem valve water inlet controlling flow to a reservoir having an elongated rectangular sectioned float pivotally supported therein on a transverse pivot at a top wall edge of the float intermediate the valve upper inlet and a subjacent reservoir outlet with the valve stem extending vertically downwardly from the valve closure plug beyond the float bottom wall wherein a slight fall in the water level pivots the float into engagement with the distal end of the stem to immediately open the valve so as to provide a fail safe operation with greater sensitivity to changes in the water level obviating the need for user adjustment of the water level in the ice maker tray throughout a domestic water pressure range of about 20 to 120 psi.

It is another object of the present invention to provide an automatic ice maker having an improved water refill arrangement including a float controlled water reservoir with a water level overflow toaccommodate incomplete ice cube release.

It is still another object of the invention to provide an automatic clear ice maker having improved water refill arrangement including a bottom outlet from the reservoir with a trough-like entry ramp to overcome water surface tension so that flow will self-start when the ice maker is first installed.

A still further object of the present invention is to provide an automatic clear ice maker having improved water refill arrangement including a nylon fill tube leading from the bottom outlet of the reservoir to a flexible adaptor having a first self-sealing interference fit with the bottom outlet of the tray.

It is yet another object of the present invention to provide an automatic clear ice maker having an improved water refill arrangement wherein a hairpinshaped, nylon sheath heater projects longitudinally into the fill tube through a second self-sealing interference fit with a flexible adaptor on the bottom outlet of the tray.

Further objects and advantages of the present invention will be apparent from the following description. reference being had to the accompanying drawings. wherein a preferred embodiment of the present invention is clearly shown.

In the Drawings:

FIG. I is a fragmentary section through the freezer compartment of a domestic refrigerator showing in side elevation the automatic clear ice maker with respect to the improved water fill system of this invention;

FIG. 2 is a front elevational view taken along line 2-2 of FIG. 1 with parts broken away to provide a schematic representation of the clear ice harvesting cycle;

FIG. 3 is a sectional view taken along the line 33 in FIG. 2;

FIG. 4 is a fragmentary sectional view along the line 4-4 in FIG. 3 showing a portion of the water fill system;

FIG. 5 is a sectional view of the improved water fill system which is the subject matter of the present invention;

FIG. 6 is a vertical sectional view taken generall along the line 66 of FIG. 5;

FIG. 7 is a perspective view of a portion of the reservoir housing showing the bottom outlet with its troughlike entry ramp;

FIG. 8 is a horizontal fragmentary sectional view taken along the line 88 of FIG. 6;

FIG. 9 is a fragmentary vertical sectional view taken along the line 9-9 of FIG. 8; and

FIG. 10 is a force-balance diagram of the float and valve.

Referring now to the drawings and more particularly to FIGS. I and 2, there is shown a frost-free household refrigerator 20 with an upper below-freezing portion 26 closed by an insulated door 30. In the disclosed form the refrigerator cabinet, which is not shown in the present application, may be of the side-by-side type wherein a right side portion encloses a refrigerated food compartment and a left side compartment encloses a lower freezer portion and the upper freezer portion 26 enclosing a clear ice maker, shown generally at 28. A description of the cabinet together with the ice maker is disclosed in the abovementioned US. Pat. No. 3,775,992, the disclosure of which is incorporated by reference herein.

In general the clear ice maker 28 includes a tray and heater assembly 34, an ice piece or ice cube grid 36 and 3 an ice storage bucket assembly 38, a weight sensing means 39 for the bucket and ice. and an ice harvesting mechanism 40, and an improved water fill system 42 which system is the subject matter of the present application.

The tray and heater assembly 34 is supported by bracket means 46 from a side wall 48 of the freezer portion. The assembly includes a drawn sheet metal housing 50 forming on one side thereof the water con taining tray 52 (FIG. 3) having a side wall 54 and a bottom wall 56, and on the other side thereofa cavity filled with Freon-filled urethane foam insulation 58. A pair of heaters 60,62 shown in FIG. 4 surround the tray 52. Heater 60 is adapted for heating all four sides 54 of the tray and thereby normally exposes the bottom side of the tray beneath the ice to above-freezing temperature. This retains the bottom portion of water along the bottom side of the tray in liquid state. For this purpose. a heater 60 is comprised of 90.8 inches of vinyl-covered resistance wire heated at l volts. 6.5-7.5 watts. 250 ohms per foot resistance.

Heater 62 is adapted for supplying additional heat to the tray bottom wall 56 under certain circumstances to keep ice from freezing all the way down to the bottom wall. The heater 60 is sandwiched between a sheet 66 of aluminum foil and a sheet 68 of aluminum foil. not shown. Also foamed in place is a tray fill tube 76 (FIG. 4) molded of plastic material such as polypropylene in heat transfer relation to heater 62 to prevent freezeup and adapted to supply water to fill tray 52 through the bottom wall 56 of the tray.

The improved water fill system 42 of the present invention will now be described with reference to FIGS. 1-8. In general the water is supplied to tray 52 from a longitudinally extending generally rectangular shaped reservoir housing 800 attached to the back wall 82 of the refrigerator behind the freezer compartment 26 by an angle bracket and housing cover plate 80b. The bracket vertical flange 800 has screws 80d secured to the back wall 82 while its horizontal flange or cover plate 80e is suitably secured as by machine screws 80f threaded in semicylindrical bosses 80g integral with the reservoir housing 800. Water 78 in the reservoir communicates with tray 52 through outlet passage 80h of conduit 801' in the reservoir housing 80a and flexible hose or tubing means 86 (shown in FIG. 3) connecting outlet passage 8011 with the tray fill tube 76 through a protector tube base 90 (FIG. 4). Water contained in tray 52 seeks a common surface level with water in the reservoir housing 80a. Thus, the desired fill level in the tray is achieved by predetermining the water level 80j in the reservoir housing 80a.

To control or maintain the surface level 80j of the water 78 in the housing 800 there is included an elongated box-shaped float 94 having a sealed cover 94a. The cover is pivotally attached by transverse pin 96 extending through a pair of spaced hinge lugs. one of which is shown at 98, secured to the top cover 940. A water valve assembly 102 includes a pair of longitudinally extending gusset plates 102a and [02b such that the holes of lugs 98 are aligned with holes in the pair of gusset plates 102a. The gusset plates 102a which are parallel with the side walls 80k and 801 of reservoir housing 800. are formed integral with horizontal web 1026 which is affixed flush to the underside of cover plate 80e by four screws 102d which are threaded in web bosses.

The water valve assembly includes a tubular valve housing' l02e. extending upwardly through a circular opening m. providing a water inlet 102fsuch that a domestic supply of purified water may be connected to inlet [02f by means of the threaded nipple portion 102g. Housed within the peripheral cylindrical couterbored inlet 102]" is a valve cage member 108 having a plurality of equally spaced projections. which in the preferred form are four projections spaced at intervals. upwardly extending in a frusto-conical manner from a peripheral washer 110 which seats in the shoulder portion 112 of the inlet and is sealed by O-ring 113. The cage 108 has a circular collar 114 positioned in axial alignment with a frusto-conical valve stopper or plug 116, preferably machined from steel material and including a rubber-like washer 117 on its undersurface. The valve plug 116 is normally urged downwardly to a seating position on a dome-sectioned valve seat 118 by the inlet water pressure together with helical compression spring 120, which has its lower end telescoped over an upwardly extending stub portion 122 of the valve plug while the spring upper end bears against the cage collar 114.

The valve plug 116 has an elongated vertical valve rod or stem 124, preferably of steel material and secured on the principal axis of the valve plug 116. The stem 124 extends concentrically through valve passage 125 when the valve is seated, while the lower free end of the stem is engaged by the leading rounded edge 126, parallel to pivot pin 96, ofa generally horizontally extending float actuator means in the form of a float probe 127 formed by an integral extension of the float bottom wall 123. As seen in FIG. 5, the free lower end of the valve stem 124 extends past the lower extremity of valve housing depending right hand guard wall 128 having opposed side flanges, one of which is shown in 129, and a central slotted opening 130 in the wall 126 aligned with the stem 124 into which the stem can swing in a vertical plane normal to pivot pin 96 in a manner to be explained. A transverse left hand guard wall 132 extends downwardly to the bottom edge of the gussets 102a.

With reference to FIGS. 5, 6 and 7 it will be seen that outlet passage 80h has a circular orifice or entrance 80 on the upper surface of first stepped portion 80n raised above the level of the float bottom wall 80p. It will be noted that the housing outlet passage 80h is located substantially vertically beneath the inlet valve port or passage 125. Tests showed that on initial fill of the reservoir housing 80a the entering water created a surface tension film over the orifice 80m preventing exiting of fill water into the tube 86 for flow to the tray 52 of the ice maker. As the diameter of the opening 80m was necessarily restricted to a maximum ID. of about 0.50 inches it was found that by providing the upper surface of step 80n with a plurality of canted drain areas sloped toward the entrance 80m, indicated at 80q, 80r and 80s the junctures of which intersect the entrance 80m, it is possible to prevent the formation of a strong surface tension film over the entrance 80m to make it self starting. and thus prevent blockage of the tube 86 on initial fill.

A second stepped portion 80! is formed at the right hand end 8014 of the reservoir housing 80a having a weir portion 80v over which excess fill water may flow into overflow cup 80w for flow out drain passage 80x into drain tube 80y to carry off any excess amount of water that may enter the housing 80a.

Reference is now made to FIG. which diagrammatically illustrates the float valve assembly system which comprises the float 94 supported on the fixed horizontal pivot pin 96 for pivotal movement or displacement in response to the rise or fall of the water level in the housing 80a. In the disclosed form the forces include the float weight W acting downwardly through the float center of gravity c.g. and a valve force F acting on the float probe 127 so as to be opposed by an equal and opposite float force F The height, length and width of the float are represented by the dimensions h, land w respectively, while the water level in the housing is shown at h,.

The total water pressure force on the valve plug 116 tending to close the valve passage 125 is represented by the force P which acts over the circular area of the valve passage having a diameter D defined by the line contact between the toroidal valve seat 118 and the bottom surface of the valve plug. The distance S is determined by the vertical distance from the valve seat to the horizontal force F, while the distance S is determined by the vertical distance from the axis of float pivot pin 96 to the horizontal force F Taking a summation of moments about point A results in the equation (water pressure force) (Diameter D/2) (Float Force) (S equals zero or:

ROW

Taking a summation of moments about point B results in the equation:

I (Bouyance Force) X (Float Weight) x ln ,order to demonstrate the effectiveness of applicants float arrangement two representative water line pressures will be used, namely a low water line pressure of psi and a high water line pressure of 120 psi.

For P 20 psi:

The change in the water lever 80j due to the change in water pressure from 120 psi to 20 psi is:

FW p

Using representative dimensions from the preferred embodiment as an example let: S 3.375 in; S 32 2.187 in;

D 0.093 in: l= 6 in; W 0.75 in; and p .().036l lb/in The result is that for an extreme range of domestic water line pressures between 20 and psi the maximum change in water level in the float will be of the order of A h 0.084 in. As the clear ice making process of applicant's automatic ice maker. disclosed in the above-mentioned patent application. requires a substantially constant water level in the fill tray 52 it will be readily appreciated that applicant has designed a novel float valve arrangement wherein this object has been achieved.

Turning now to FIGS. 8 and 9, applicant's fill tube heater arrangement will now be described. As seen in FIG. 8 the right angled elbow section 86 directs the water from the vertical passage 80h into the horizontal fill tube portion 77 which in the instant form is made of nylon material. The tube 77 extends through a circular opening 142 in the back wall 82 of the refrigerator cabinet defined by the spool-like plastic grommet 144 the flanged ends 146 and 147 of which are in flush engagement with the inner surfaces of the outer shell wall casing 82 and the inner liner 148 respectively.

The tube 77 extends through insulated wall 149 of freezer duct 150 at the rear of the freezer compartment 26 and into plastic fill tube adapter 151 having an opening 152 in its top wall for connection with the tray vertical fill tube 154 integral with enlarged bore 156 formed in one corner of the tray bottom wall 158. The adapter 151 is supported in insulated plastic ice maker mechanism housing or box 160 secured to the tray assembly boss 161 on its bottom wall by a horizontal ear member 162 connected by screw 164 to the boss 161. It will be noted that bracket 172 engages hook member 174 of the tray assembly to support same on the cabinet side wall 48.

A fill tube heater member, generally indicated at 180, is positioned within the fill tube 177 and extends from a rearmost location within the cabinet rear wall to a forwardmost location extending through the front wall 182 of the adapter 151. The heater member includes an outer oval sectioned rubber or plastic insulation sheath or cover 184 having its major transverse axis extending vertically to provide a vertical position. The looped resistance heater wire 186 separated by divider insulation 185 is located adjacent the upper and lower portions of the fill tube. In this manner it will be appreciated that the flow of water entering the tray will be divided into two flow streams as indicated by the dashed arrows in FIG. 8.

While the embodiment of the present invention as herein disclosed constitutes a preferred form, it is to be understood that other forms might be adopted.

1 claim:

1. In combination with an insulated cabinet wall defining a freezer compartment adapted to contain air at subfreezing temperatures, an ice maker in said freezer compartment, said ice maker comprising a tray on the inside of said insulated cabinet wall having side and bottom tray walls adapted to contain water therein at a predetermined level, cooling means supplying air at subfreezing temperatures to the water contained in said tray at said predetermined level, and water fill means for refilling said tray with water to said predetermined level, said fill means including a reservoir housing adapted to contain water therein in a liquid state at said predetermined level and means for maintaining water in said housing at said predetermined level, said 7 last named means including a float pivotally supported about a transverse axis in said housing, an inlet valve positioned in the housing top wall adjacent one end thereof adapted for supplying a water level to said housing from a domestic supply of water available at pressures normally between about 20 pounds per square inch and 120 pounds per square inch, an outlet positioned in the bottom wall of said housing. said inlet valve having an annular valve seat, a valve plug engaging in one position against said seat to close an inlet port, said plug having a centrally positioned stem extending through said valve port for limited tilting movement, said float responsive to the level of liquid in said housing and pivotally connected in said housing at a point-intermediate said valve seat and the normal water level in said housing, said float having probe means at its lower end contacting said valve stem, said probe means being operable to overcome the line water pressure force on said plug and tilt said stem and plug and open said port whenever said float pivots downwardly below a predetermined minimum level of water in said housing. and whereby the incoming water causes said float to pivot upwardly to said predetermined level causing the water pressure force on said valve plug to immediately return said stem to its vertical position to close said port.

2. In combination with an insulated cabinet wall defining a freezer compartment adapted to contain air at subfreezing temperatures, a clear ice maker in said freezer compartment, said clear ice maker comprising a tray on the inside of said insulated cabinet wall having side and bottom tray walls adapted to contain water therein at a predetermined level, cooling means supply ing air at sub-freezing temperatures to the top surface of the water contained in said tray at said predetermined level for a sufficient period to start freezing an upper portion of said water from said top surface downwardly into clear ice, heating means maintaining a bottom portion of said water in a liquid state adjacent said bottom tray wall, and water fill means for refilling said tray with water to said predetermined level when the upper clear ice portion is removed from said tray. said fill means including an elongated box-shaped reservoir housing adapted to contain water therein in a liquid state at said predetermined level and means for maintaining water in said housing at said predetermined level, the improvement wherein said last named means includes an elongated box-shaped float pivotally supported at an upper corner edge about a transverse axis in said housing, an inlet valve positioned in the housing top wall adjacent one end thereof adapted for supplying a water level to said housing from a domestic supply of water available at pressures normally between about 20 pounds per square inch and I20 pounds per square inch, an outlet positioned in the bottom wall of said housing communicating with said tray, said inlet valve having a valve seat. a valve plug engaging in one position against said seat to close the valve inlet port, said plug having a centrally positioned stem extending through said inlet port for tilting movement, said float responsive to the level of liquid in said housing with its pivotal transverse axis located intermediate said valve seat and the normal water level in said housing, said box-shaped float having a shape substantially conforming to that of said elongated box-shaped housing, said float having probe means at its lower corner edge contacting said valve stem, said probe means being operable to overcome the line water pressure force acting on said plug and tilt said stem to open said port whenever said float pivots downwardly below a predetermined minimum level of water in said housing, and whereby the incoming water allowing said float to pivot upwardly to said predetermined level causing the water pressure force on said plug to immediately return said stem to its vertical position to close said port.

3. In combination with an insulated cabinet wall defining a freezer compartment adapted to contain air at subfreezing temperatures, an ice maker in said freezer compartment, said ice maker comprising a tray on the inside of said insulated cabinet wall having side and bottom tray walls adapted to contain water therein at a predetermined level, cooling means supplying air at sub-freezing temperatures to the water contained in said tray at said predetermined level, and water fill means for refilling said tray with water to said predetermined level, said fill means including a reservoir housing adapted to contain water therein in a liquid state at said predetermined level and means for maintaining water in said housing at said predetermined level, said last named means including a float pivotally supported about a transverse axis in said housing, an inlet valve positioned in the housing top wall adjacent one end thereof adapted for supplying a water level to said housing from a domestic supply of water available at pressures normally between about 20 pounds per square inch and pounds per square inch, an outlet positioned in the bottom wall of said housing, said inlet valve having an annular valve seat, a valve plug engaging in one position against said seat to close an inlet port, said plug having a centrally positioned stem extending through said valve port for limited tilting movement, said float responsive to the level of liquid in said housing and pivotally connected in said housing at a point intermediate said valve seat and the normal water level in said housing, said float having probe means at its lower end contacting said valve stem, said probe means being operable to overcome the line water pressure force on said plug and tilt said stem and plug and open said port whenever said float pivots downwardly below a predetermined minimum level of water in said housing, and whereby the incoming water causes said floatto pivot upwardly to said predetermined level causing the water pressure force on said valve plug to immediately return said stem to its vertical position to close said port, said housing outlet having its inlet entrance in a stepped portion of said bottom wall, the surface of said stepped portion having a plurality of canted drain areas sloped toward said entrance to prevent the formation of a blocking surface tension film whereby the initial fill of water into said housing flows therefrom to said tray in a self starting manner.

4. In combination a refrigerator including an insulated cabinet wall defining a freezer compartment adapted to contain air at sub-freezing temperatures, an ice maker in said freezer compartment, said ice maker comprising a tray on the inside of said insulated cabinet wall having side and bottom tray walls adapted to contain water therein at a predetermined level, cooling means supplying air at sub-freezing temperatures to the water contained in said tray at said predetermined level, and water fill means for refilling said tray with water to said predetermined level, said fill means including a reservoir housing adapted to contain water therein in a liquid state at said predetermined level and means for maintaining water in said housing at said predetermined level, said last named means including a 9 float pivotally supported about a transverse axis in said housing, an inlet valve positioned in the housing top wall adjacent one end thereof adapted for supplying a water level to said housing from a domestic supply of water, an outlet positioned in the bottom wall of said housing, a heated plastic water fill tube having an inlet located outside of said refrigerator connected to the outlet of said reservoir housing and an outlet connected to said tray, said fill tube having a heater member substantially coextensive with the portion of said tube within said freezer compartment, said heater including 10 a looped electrical resistance wire encased in an outer elongated oval sectioned insulation cover having its major axis positioned vertically such that said heater member forms a vertical partition within said tube, whereby the flow of fill water through said tube portion in said freezer compartment and communicating with said tray will be divided into two parallel streams contacting said heater member whereby the water therein is maintained at a temperature above freezing. 

1. In combination with an insulated cabinet wall defining a freezer compartment adapted to contain air at subfreezing temperatures, an ice maker in said freezer compartment, said ice maker comprising a tray on the inside of said insulated cabinet wall having side and bottom tray walls adapted to contain water therein at a predetermined level, cooling means supplying air at sub-freezing temperatures to the water contained in said tray at said predetermined level, and water fill means for refilling said tray with water to said predetermined level, said fill means including a reservoir housing adapted to contain water therein in a liquid state at said predetermined level and means for maintaining water in said housing at said predetermined level, said last named means including a float pivotally supported about a transverse axis in said housing, an inlet valve positioned in the housing top wall adjacent one end thereof adapted for supplying a water level to said housing from a domestic supply of water available at pressures normally between about 20 pounds per square inch and 120 pounds per square inch, an outlet positioned in the bottom wall of said housing, said inlet valve having an annular valve seat, a valve plug engaging in one position against said seat to close an inlet port, said plug having a centrally positioned stem extending through said valve port for limited tilting movement, said float responsive to the level of liquid in said housing and pivotally connected in said housing at a point-intermediate said valve seat and the normal water level in said housing, said float having probe means at its lower end contacting said valve stem, said probe means being operable to overcome the line water pressure force on said plug and tilt said stem and plug and open said port whenever said float pivots downwardly below a predetermined minimum level of water in said housing, and whereby the incoming water causes said float to pivot upwardly to said predetermined level causing the water pressure force on saId valve plug to immediately return said stem to its vertical position to close said port.
 2. In combination with an insulated cabinet wall defining a freezer compartment adapted to contain air at subfreezing temperatures, a clear ice maker in said freezer compartment, said clear ice maker comprising a tray on the inside of said insulated cabinet wall having side and bottom tray walls adapted to contain water therein at a predetermined level, cooling means supplying air at sub-freezing temperatures to the top surface of the water contained in said tray at said predetermined level for a sufficient period to start freezing an upper portion of said water from said top surface downwardly into clear ice, heating means maintaining a bottom portion of said water in a liquid state adjacent said bottom tray wall, and water fill means for refilling said tray with water to said predetermined level when the upper clear ice portion is removed from said tray, said fill means including an elongated box-shaped reservoir housing adapted to contain water therein in a liquid state at said predetermined level and means for maintaining water in said housing at said predetermined level, the improvement wherein said last named means includes an elongated box-shaped float pivotally supported at an upper corner edge about a transverse axis in said housing, an inlet valve positioned in the housing top wall adjacent one end thereof adapted for supplying a water level to said housing from a domestic supply of water available at pressures normally between about 20 pounds per square inch and 120 pounds per square inch, an outlet positioned in the bottom wall of said housing communicating with said tray, said inlet valve having a valve seat, a valve plug engaging in one position against said seat to close the valve inlet port, said plug having a centrally positioned stem extending through said inlet port for tilting movement, said float responsive to the level of liquid in said housing with its pivotal transverse axis located intermediate said valve seat and the normal water level in said housing, said box-shaped float having a shape substantially conforming to that of said elongated box-shaped housing, said float having probe means at its lower corner edge contacting said valve stem, said probe means being operable to overcome the line water pressure force acting on said plug and tilt said stem to open said port whenever said float pivots downwardly below a predetermined minimum level of water in said housing, and whereby the incoming water allowing said float to pivot upwardly to said predetermined level causing the water pressure force on said plug to immediately return said stem to its vertical position to close said port.
 3. In combination with an insulated cabinet wall defining a freezer compartment adapted to contain air at subfreezing temperatures, an ice maker in said freezer compartment, said ice maker comprising a tray on the inside of said insulated cabinet wall having side and bottom tray walls adapted to contain water therein at a predetermined level, cooling means supplying air at sub-freezing temperatures to the water contained in said tray at said predetermined level, and water fill means for refilling said tray with water to said predetermined level, said fill means including a reservoir housing adapted to contain water therein in a liquid state at said predetermined level and means for maintaining water in said housing at said predetermined level, said last named means including a float pivotally supported about a transverse axis in said housing, an inlet valve positioned in the housing top wall adjacent one end thereof adapted for supplying a water level to said housing from a domestic supply of water available at pressures normally between about 20 pounds per square inch and 120 pounds per square inch, an outlet positioned in the bottom wall of said housing, said inlet valve having an annular valve seat, a valve plug engaging in one position against said seat to close an inlet port, said plug having a centrally positioned stem extending through said valve port for limited tilting movement, said float responsive to the level of liquid in said housing and pivotally connected in said housing at a point intermediate said valve seat and the normal water level in said housing, said float having probe means at its lower end contacting said valve stem, said probe means being operable to overcome the line water pressure force on said plug and tilt said stem and plug and open said port whenever said float pivots downwardly below a predetermined minimum level of water in said housing, and whereby the incoming water causes said float to pivot upwardly to said predetermined level causing the water pressure force on said valve plug to immediately return said stem to its vertical position to close said port, said housing outlet having its inlet entrance in a stepped portion of said bottom wall, the surface of said stepped portion having a plurality of canted drain areas sloped toward said entrance to prevent the formation of a blocking surface tension film whereby the initial fill of water into said housing flows therefrom to said tray in a self starting manner.
 4. In combination a refrigerator including an insulated cabinet wall defining a freezer compartment adapted to contain air at sub-freezing temperatures, an ice maker in said freezer compartment, said ice maker comprising a tray on the inside of said insulated cabinet wall having side and bottom tray walls adapted to contain water therein at a predetermined level, cooling means supplying air at sub-freezing temperatures to the water contained in said tray at said predetermined level, and water fill means for refilling said tray with water to said predetermined level, said fill means including a reservoir housing adapted to contain water therein in a liquid state at said predetermined level and means for maintaining water in said housing at said predetermined level, said last named means including a float pivotally supported about a transverse axis in said housing, an inlet valve positioned in the housing top wall adjacent one end thereof adapted for supplying a water level to said housing from a domestic supply of water, an outlet positioned in the bottom wall of said housing, a heated plastic water fill tube having an inlet located outside of said refrigerator connected to the outlet of said reservoir housing and an outlet connected to said tray, said fill tube having a heater member substantially coextensive with the portion of said tube within said freezer compartment, said heater including a looped electrical resistance wire encased in an outer elongated oval sectioned insulation cover having its major axis positioned vertically such that said heater member forms a vertical partition within said tube, whereby the flow of fill water through said tube portion in said freezer compartment and communicating with said tray will be divided into two parallel streams contacting said heater member whereby the water therein is maintained at a temperature above freezing. 